Reciprocating piston pumps, in particular for the injection of fuel



Aug. 2, 1960 P. E. BESSIERE 2,947,257

- RECIPROCATING PISTON PUMPS, IN PARTICULAR FOR THE INJECTION 0F FUEL Filed June 9, 1958 3 Sheets-Sheet 1 .i l I INVENTOR E Rem: Ewe/viva Bessie:

1950 P. E. BESSIERE 2,947,257

RECIPROCATING PISTON PUMPS, IN PARTICULAR FOR THE INJECTION OF FUEL Filed June 9, 1958 3 Sheets-Sheet 2 Q? m m- \H H" INVENTOR 6 i g ATTORNEY I9 Aug. 2., 1960 P. E. BESSIERE 2,947,257

RECIPROCATING PISTON PUIIPS, IN PARTICULAR FOR THE INJECTION OF FUEL Filed June 9, 1958 V 3 Sheets-Sheet 3 Z0 /7f Q ///7 21a INVEN TOR B ZTTOENEY United States. Patent M RECIPROCATING PISTON PUMPS, IN PARTICU- LAR FOR THE INJECTION OF FUEL Pierre Etienne Bessiere, 5 Blvd. du Commandant Charcot, Neuilly-sur-Seine, France Filed June 9, 1958, Ser. No. 740,843

Claims priority, application France June 12, 1957 Claims. (Cl. 103-41) The present invention relates to reciprocating piston pumps serving in particular to the injection of fuel, in which a main piston driven by external means, in particular by one shaft of the engine on which is mounted the pump acting as fuel injection pump, drives, through a hydraulic transmission an auxiliary piston (also called shuttle piston) in the direction which causes it to deliver fuel from the pump whereas the length of the return strokes of said auxiliary piston, which determines the amount of fuel delivered during the next delivery stroke, is adjustable by means of a mechanical abutment of variable position.

The object of this invention is to simplify the construction of such pumps and to make their operation more reliable.

According to the invention, the conduit which conveys fuel or any other liquid to the auxiliary cylinder chamber from which starts the delivery conduit of the pump, is alternately closed and opened either directly by the main piston or by a part, preferably in the form of a slide valve, controlled by thislast mentioned piston. According to a first embodiment of the invention, applicable chiefly to injection pumps for relatively heavy fuels such as the oils used in Diesel engines and the like, said fuel conveying conduit connects together the two chambers of the auxiliary cylinder located on either side of the auxiliary piston whereby at least a portion of the liquid which, during one delivery stroke, has transmitted the movement of the main piston to the auxiliary piston is transferred, asfuel to be injected, by the auxiliary piston during the return stroke thereof, into the auxiliary cylinder chamber from which starts the pump delivery conduit.

According to a second embodiment of the invention, which is particularly suitable for light fuel injection pumps and in particular for gasoline injection pumps, the circuit of the liquid which serves during the delivery strokes to transmit the movement of the main piston to the auxiliary piston is wholly separate from the light fuel circuit, the first circuit containing a liquid, such as oil, which has good lubricating properties. 7 Preferred embodiments of the present invention will be hereinafter described with reference to the accompartying drawings, given merely by way of example and in which:

Fig. 1 is a diagrammatic sectional view of an injection pump in which the fuel to be delivered also constitutes the hydraulic transmission liquid interposed between the main and the auxiliary pistons;

. Fig. 2 shows a pump similar to that of Fig. 1 in which the position of the abutment which determines the deliveryrate of th epump' is controlled by hydraulic regu- A lating means;

Fig. 3 shows two modifications of a detail;

Figs. 4 and 5 show two modifications of gasoline pump made according to the invention. Each'of the pumps shown-by the drawings includes a main piston'l which is given a reciprocating movement 7 r by the shaft of the engine on which the injection pump is mounted through any suitable means such as a cam (not shown on the drawings). This piston is moving in the main cylinder 2 of the pump, into which opens a feed conduit 3 through which liquid is conveyed to said cylinder from a transfer pump of the conventional type.

During the upward movement of piston 2 (delivery stroke), said piston, after closing the outlet of feed conduit 3, delivers the liquid enclosed in cylinder 2 into the chamber 5a of an auxiliary cylinder which contains an auxiliary or shuttle piston 6 which divides cylinder 5into two chambers 5a and 5b. From chamber Sbstarts a delivery conduit 7 in which is provided a check valve 8. Under the effect of the liquid delivered into chamber 511 shuttle 6 moves in auxiliary cylinder 5 against the action of a return spring 9 until the lower edge of said shuttle clears a discharge conduit 10 starting from an intermediate point of cylinder 5. During this movement, piston 6 delivers a portion of the liquid present in chamber 5b past check valve 8 into delivery conduit 7 which leads to the injector or injectors of the engine on which the injection pump is mounted.

In the pump shown by Figs. 1 and 2 the liquid which enters cylinder 2 through conduit 3 is also the liquid to be delivered by the pump. In order to feed at least a portion of this liquid to chamber 5b, from which starts deliveryconduit 7, chambers 5a and 5b are connected together by means of a conduit 11 which by-passes shuttle 6 and in which is mounted -a control member 12 constituted by a slide valve which closes conduit 11 during the upward stroke of main piston 1 and opens said conduit when piston 1 is moving downwardly or is stopped in its lower dead center position.

In order to obtain such an operation of slide valve 12, this slide valve is mounted in a cylinder 13 and subjected to the return action of a spring 14, the lower end of cylinder 13 communicating constantly through a conduit 15 with cylinder 2. Furthermore, slide valve 12 is provided with a transverse passage or a groove 16 so located in said slide valve that it opens conduit 11 when slide valve 12 is applied by spring 14 in its position of rest (as shown by Fig. 1). On the contrary when piston 1 is moving upwardly the. pressureexisting in cylinder 2 moves slide valve 12 upwardly so that it closes conduit 11.

The upward movement of slide valve 12 is stopped by an abutment 17 provided in cylinder 13.

Furthermore, in the passage extending between cylinder 2 and cylinder 5, there .is mounted a check valve 4 which opens in the direction from cylinder 2 toward cylinder 5 Advantageously the return forces which-act upon slide valve. 12 and check valve 4 respectively are determined in such a manner thatslide valve 12 closes conduit 11 before check valve 4 opens to'let the liquid discharged by piston 1 pass into the chamber 5a of cylinder 5. Owing to the provision of slide valve 12 in conduit 11, when piston 1 moves upwardly the liquid delivered by said piston enters the chamber 5a of cylinder 5- without being able 'top'ass at this time through conduit 11 to the chamber5b of cylinder 5. On the contrary when piston 1 starts in its downward movement and shuttle 6 also moves in cylinder 5 under the action ofgspring 9 (downwardly in the example of Fig. 1) the liquid present in chamber 5a is transferre'd by shuttle 6 into chamber 5b through conduit 11 which is now opened. The amount of liquid thus transferred is the greater as the downward stroke of shuttle 6 after it has closed discharge conduit 10 is longer. This amount is subsequently delivered through conduit 7 on the next upward stroke of piston 1 andshuttle6. a V In order to meter the amount of fuel transferred by shuttle 6 from chamber 511 to chamber 511 through conduit 11 the return stroke of the shuttle is controlled by means of an adjustable mechanical abutment. According to anadvantageous embodiment of the invention this abutment is constituted by a rod .18 projecting into chamber a and carried by a screw 19 adjustably engaged in a screw-threaded housing 28 provided in the pump body.

Obviously the amount transferred by the shuttle, during every downward stroke thereof, to chamber 5b is the smaller as a greater length of rod 18 is projecting into said chamber 5b.

This adjustment is independent of the speed of piston l and depends only upon the position of said rod 18. Of course this position may be modified either at will, for instance manually or by means of a pedal, or automatically in accordance with the variations of a suitable factor which is to influence the amount of fuel delivered by the pump. This factor may be the atmospheric pressure, the temperature, the amount of exhaust gases escaping from the engine, the amount of air entering the engine, the speed of the engine, and so on. This factor may be materialized by any regulating device which controls the position of rod 8.

Fig. 2 shows a pump similar to that of Fig. 1 the axis of the auxiliary cylinder 5 being in this case at right angles to the axis of main cylinder 2.

In the embodiment shown by Fig. 2 the position of rod 18 is controlled by a speed regulating device.

This device includes a chamber 21 fed with liquid from a pump (for instance a gear pump 22) driven at a speed proportionnal to the value of the adjustment factor. This pump 22 may be the fuel transfer pump, in which case the liquid supplied to chamber 21 is the fuel itself and the adjustment factor is the speed of the engine on which the injection pump is mounted.

Chamber 21 is one of the chambers limited in its cylinder by a piston 23, one of the sides of which is subjected to the pressure of the liquid present in said chamber 21 whereas a return spring 24 pushes the other side of said piston 23 in the opposed direction. The movements of piston 23 in its cylinder under the action of a variation of the pressure of the liquid in chamber 21 are transmitted to abutment 18 through a rack 25 rigid with piston 23 and a toothed wheel 26 rigid with screw 19 which carries rod .18.

Liquid can fiow out from chamber 21 through a conduit 27 starting from chamber 21 (or from the conduit extending between pump 22 and said chamber) and provided with throttling means, preferably adjustable. For instance, as shown by Fig. 2, a slide valve 28 extending across conduit 27 is provided with a groove 29, this slide valve being movable in its housing against the action of a spring 13 preferably adjustable by means of a screw 31. In its position of rest, slide valve 28 is applied by spring 30 against an abutment which may be either fixed or adjustable. In the construction of Fig. 2 there is a fixed abutment, constituted by a shoulder 32, which determines the maximum cross section area of the passage afforded by slide valve 28 in conduit 27 (position shown by Fig. 2) and furthermore there is an abutment 33 adjustable by means of a screw 34 so that it is possible to give this cross section area any value lower than said maximum value and even to reduce it to zero.

Furthermore and advantageously, the part which determines the cross section area of the throttle portion of conduit 27 is subjected to the pressure existing in chamber 21. This pressure may act upon this part either to increase said cross section area or it may also, as shown by Fig. 2, tend to reduce this cross section. In the construction of Fig. 2, this area is maximum when slide valve 28 is applied against fixed abutment 32 or adjustable abutment 33. But the end of slide valve 28 is engaged in a space 35 communicating through a conduit 36 with chamber 21 or with a portion of conduit 27 located upstream of groove 29,v so that slide valve 28 is urged 4 toward the left by the pressure of the liquid in space 35.

In the construction of Fig. 2 the top part of the cylinder of piston 23 is provided with two openings 37 and 38. Opening 37 serves to evacuate the small amounts of liquid which may have leaked past piston 23 whereas opening 38' is placed in communication with chamber 21 when, due to the closing of the throttled portion of conduit 27, piston 23 is in its uppermost position in its cylinder. Thus the pressure in chamber 21 cannot reach values such as they might cause bursting of the conduits.

The operation of the pump of Fig. 2 is as follows:

As long as the engine is running at a speed below a given value, spring 24 applies piston 23 against a shoulder 39 provided at the lower part of chamber 21. For this position of piston 23, rod 18 projects very little into chamber 5a and therefore the maximum amount of fuel is injected by the pump. Furthermore the cross section area of the portion of conduit 27 throttled by slide valve 28 is maximum. if, due to a reduction of the load, the speed of the engine increases, the pressure also increases in chamber 21 and in chamber 35. This pressure, due to the law determining the flow of a liquid through a throttled passage, increases quicker than the rate of flow of the liquid, which is a direct function of the speed of the engine which drives pump 22. If the speed of the engine rises above the above mentioned given value, the pressure in chamber 35 acts upon slide valve 28 to push it against the action of spring 30, thus reducing the cross section area of the throttled portion of conduit 27. This further increases the pressure, which finally increases much more quickly than the speed. Piston 23 leaves its seat 39 and moves in its cylinder against the action of spring 24, producing a displacement of rod 18 which reduces the amount of fuel injected on every stroke of the pump.

The speed of the engine ceases to increase when a balanced position is reached for which neither piston 23 nor slide valve 28 are resting upon their respective seats. If a variation of the load causes a small variation of speed of the engine, this produces an important variation of the pressure in chamber 21, which variation immediately corrects the speed variation. If the variation of speed becomes too great the throttled portion of conduit 27 is wholly closed by the slide valve 28 so that piston 23 moves until it clears the discharge opening 38. At the same time, the end of rod 18 comes opposite discharge conduit 10, which stops the feed of fuel from chamber 5b to chamber 5a and therefore the injection of fuel to the engine cylinders. This constitutes the limit speed of the engine.

This limit speed depends upon the adjustment of spring 30. By acting merely upon this spring it is therefore possible to vary the limit speed at the same time as the running speed. An all speed control is thus obtained.

If only abutment 33 is acted upon by means of screw 34, a fixed limit speed is obtained. 7

Advantageously, the speed of the displacements of mechanical abutment 18 may be limited by a dash-pot (not shown on the drawing) located for instance at the end of the rack 25.

According to a modification, the fineness of regulation may be further improved by using, for the adjustment of the throttled portion of conduit 27, conjugate cross sections so shaped that the reduction of the cross section area of the throttled portion increases the more rapidly as the part which controls the cross section area of the throttled portion (slide valve 28) is coming nearer to the position of full closing of the throttled portion. In this case, the groove 29 of slide valve 28 is replaced by a channel at right angles to the axis of said slide valve.

Two embodiments of such conjugate sections are shown by Fig. 3. According to one of these embodiments the sections a and b, respectively of conduit 27 and of the channel provided in the slide valve, are of triangular shape whereas in the other embodiment said cross sections have a semi-circular shape. Inboth cases the passage through the throttled portion corresponds to the area over which sections a and b overlap and are indicated on Fig. 3 by cross hatchings.

Figs. 4 and 5 show pumps for the injection of a light fuel such as gasoline. They differentiate from the pumps shown by Figs. 1 and 2 by the fact that the circuit of the liquid which ensures the hydraulic transmission between pistons 1 and 6 during their delivery strokes is distinct from the circuit of the light fuel to be delivered by the pump. The liquid which ensures said hydraulic transmission and which is constituted by oil or another liquid having good lubricating properties enters cylinder 2 through conduit 3, the outlet of which is cleared by piston 1 when said piston is in its lowermost position whereas the fuel directly enters chamber 5b through a conduit 11a controlled, through means which will be hereinafter described, in accordance with the movement of main piston 1.

The communication between cylinder 2 and chamber 5b is ensured by a conduit 4 open in both directions.

It should be noted that the reference numerals used in the description of Figs. 1 and 2 designate the same parts on Figs. 4 and 5.

Conduit 11a is controlled in such manner as to be opened at least during a portion of the time period between the beginning of the downward movement of piston 1 and the beginning of its next upward movement. Thus in the embodiment of Fig. 4 conduit 11a opens into cylinder 2 below feed conduit 3. Furthermore, at the same level as conduit 11a, there is provided a second conduit 11b opening also into cylinder 2. Conduit 11b is connected with the delivery of a transfer pump which supplies the light fuel to be fed to chamber 5b. This transfer pump is of course distinct from the transfer pump which feeds oil to cylinder 2 through conduit 3.

In order to ensure the communication between conduits 11b and 11a when piston 1 is in its lowermost position, this piston is provided (Fig. 4) with a groove 40.

Chamber 5b is therefore fed with an amount of gasoline or light fuel which is the greater as rod 18 is projecting to a greater distance into chamber 5a.

However, whatever be the position of said rod 18, the beginning of the delivery stroke of shuttle 6 and therefore the beginning of fuel injection always coincide with the time when piston 1, during its upward stroke, closes the outlet of conduit 3.

In the modification of Fig. 5, control of conduits 11a and 11b is ensured by slide valve 12a provided with a groove 16a and actuated on the one hand by the pressure of oil in cylinder 2, transmitted through a conduit 15a, and on the other hand by spring 14a.

When piston 1 is moving upwardly the pressure of the liquid displaces slide valve 1.2a so that said slide valve closes the communication between 11b and chamber 5b, the movement of slide valve 12a being then for instance a downward movement, until a projection 17a of the slide valve is applied against the bottom of cylinder 13a. On the contrary, as soon as piston 1 has started on its downward movement, slide valve 12a is pushed by spring 14a toward the position shown by Fig. 5 where groove 16a connects conduits 11b and 11a together so that the light fuel can be fed to chamber 5b. Slide valve 12a remains in its position until, at the end of its next upward movement, piston 1 again closes the feed conduit 3.

It results from the preceding description that in the pump shown by Figs. 4 and 5 the circuit containing the light'fuel to be delivered by the pump is separate from the circuit of the liquid having good lubricating qualities, which insures the hydraulic transmission between pistons 1 and 6. In cylinder 5 this separation is ensured merely by piston 6. The presence of oil having good lubricating qualities in the chamber 5a of cylinder 5 ensures a good lubrication of shuttle piston 6 and compensates for the slight defect of lubricating qualities inherent in the light fuel'present in chamber 5b.- In or; der further to improve the lubricating effect, in'cylinder .5, of the liquid present in chamber 5a, piston 6 may be provided in its middle part with a groove 41 constantly in communication with chamber 5a through a channel 42 extending through a portion of said piston 6.

Of course, the pumps of Figs. 4 and 5 may be used for delivering any light fuel having poor lubricating quali- .ties, that is to say not only gasoline, but also kerosene, ether, etc. v

The invention is not limited to the particular embodiments above described, but it also includes modifications thereof within the scope of the appended claims. I

For instance, in the pumps shown by Figs. 4 and 5 the return movement of auxiliary piston 6 may be achieved not by a spring but by the pressure of gasoline or any other light fuel fed into chamber 5b during the period for which feed conduit 11b is opened.

The pump according to the invention, instead of serving to the injection of'fuel, might serve to supply with liquid a hydraulic circuit for the transmission of energy.

The pump according to the present invention may be a multi-cylinder pump driven through any suitable means such as a crank-shaft, an oscillating disc, a system of cams, etc. the whole of the abutments 18 of the respective cylinders being advantageously controlled by a single device such as a rack, a cam and so on, whereby the delivery rate is the same for all the cylinders.

The invention might also apply to a reciprocating pump for supplying liquid to an energy distributing hydraulic circuit,,in which the position of abutment 18 is varied as a function of the pressure existing in said'hydraulic circuit or in an accumulator connected therewith.

What I claim is:

1. A reciprocating piston pump which comprises, in combination, a main cylinder, 21 main piston mechanically actuated to reciprocate in said cylinder, an auxiliary cylinder fixed with respect to said main cylinder, an auxiliary piston freely movable in said auxiliary cylinder,

said auxiliary piston dividing said auxiliary cylinder in two chambers, located respectively on opposite sides of said auxiliary piston, a delivery pipe starting from the end of one of said chambers, means for'urging said auxiliary piston in the direction which reduces the volume of the other of said chambers, said second mentioned .chamber being in communication with said main cylinder, at least for the flow of liquid from said main cylinder to said second mentioned chamber, mechanical abutment means adjustably carried by said auxiliary cylinder for limiting the displacements of said auxiliary piston in the direction which reduces the volume of said second mentioned chamber, a discharge conduit leading out from said auxiliary cylinder and starting from a point of the wall thereof intermediate between the ends thereof, means forming a source of liquid under pressure, a conduit leading from said source to said first mentioned chamber for the feed of liquid thereto, and control means operative by said main piston for connecting said conduit with said source at least at the end of the outward stroke of said main piston whereby liquid is then fed to said first mentioned chamber and for cutting off said conduit from said source during every inward stroke of said main piston, when liquid is then expelled by said auxiliary piston from said first mentioned chamber into said delivery pipe.

2. A pump according to claim 1 in which said control means consist of a slide valve mounted across said conduit and hydraulically operated in response to variations of the liquid pressure in said main cylinder.

Y 3. A pump according to claim 1 in which said source of liquid under pressure is constituted by said second mentioned chamber.

4. A pumpaccording to claim 1 in which said mechanical abutment means consist of a screw threaded rod ad- 7 justably screwed in the end of said auxiliary cylinder that limits said second mentioned chamber, said rod being parallel to the axis of said auxiliary cylinder andextending into said second mentioned chamber.

5. A pump according to claim 1 in which said mechanical abutment means consist of a screw threaded rod adjustably screwed in the end of said auxiliary cylinder that limits said second mentioned chamber, said rod being parallel to the axis of said auxiliary cylinder and extending into said second mentioned chamber, the pump further including a regulating device for controlling said rod responsive to variations of a physical factor of ad justment for rotating said screw-threaded rod. 7

6. A pump according to claim 1 in which said mechanical abutment means consist of a screw threaded rod adjustably screwed in the end of said auxiliary cylinder that limits said second mentioned chamber, said rod being parallel to the axis of said auxiliary cylinder and extending into said second mentioned chamber, the pump further including a regulating device for controlling said rod responsive to variations of the speed of reciprocation of said main piston.

7. A pump according to claim 1 in which said mechanical abutment means consist of a screw threaded rod adjustably screwed in the end of said auxiliary cylinder that limits said second mentioned chamber, said rod being parallel to the axis of said auxiliary cylinder and extending into said second mentioned chamber, the pump further including a regulating device for controlling said rod responsive to variations of a physical factor of adjustment for rotating said screw-threaded rod and means for stopping the inward displacement of said rod in said second mentioned chamber tothe position where said auxiliary piston clears the opening of said discharge conduit.

8. A reciprocating piston pump which comprises, in combination, a main cylinder, a main piston mechanically actuated to reciprocate in said cylinder, an auxiliary cylinder fixed with respect to said main cylinder, an auxiliary piston freely movable in said auxiliary cylinder, said auxiliary piston dividing said auxiliary cylinder in two chambers, located respectively on opposite sides of said auxiliary piston, a delivery pipe starting from the end of one of said chambers, resilient means for urging said auxiliary piston in the direction which reduces the volume of the other of said chambers, said second men- 8 tioned chamber being in communication with said main cylinder, mechanical abutment means adjustably carried by said auxiliary cylinder for limiting the displacements of said auxiliary piston in the direction which reduces the volume of said second mentioned chamber, a discharge conduit leading out from said auxiliary cylinder and starting from a point of the Wall thereof intermediate between the ends thereof, an external source of liquid under pressure having no communication with said second mentioned chamber and the portion of said main cylinder that communicates therewith, a conduit leading from said source .to said first mentioned chamber for the feed of liquid thereto, and valve means in said conduit operative by said main piston for connecting said conduit with said source at least at the end of the outward stroke of said main piston whereby liquid is then fed to said first mentioned chamber and for cutting oif said conduit during every inward stroke of said main piston, when liquid is then expelled by said auxiliary piston from said first mentioned chamber into said delivery pipe.

9. A pump according to claim 1 further including a pressure responsive regulating device for adjusting the position of said mechanical abutment means with respect to said auxiliary cylinder, said device including a casing, means for feeding said casing with a liquid at a pressure proportional to the speed at which said main piston is reciprocated in said main cylinder, means responsive to variation of the liquid pressure in said casing and operatively connected with'said abutment means for positioning said abutment means in accordance with the value of said last mentioned pressure, outlet means in said casing to permit outflow of liquid therefrom and means responsive to variation of said last mentioned pressure to control the outflow rate through said outlet means in accordance with the value of said last mentioned pressure.

10. A pump according to claim 9 in which said outfiow rate is increased in response to increases of said last mentioned pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,281,045 Outin Apr. 28, 1942 2,576,747 Bryant Nov. 27, 1951 FOREIGN PATENTS 402,603 Great Britain Dec. 7, 1933 

